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MECHANICS OF WHEEL AND RAIL

Tire-profiling tests undertaken in New South Wales to reduce oscillation resulted in an increase in the severity of the oscillations, which was directly traceable, not to the contact of the flange root with the edge of the rail, but of the steeply inclined portion of the tread adjoining the flange root. This is a well-known characteristic of all worn or hollow tire profiles. The objective of the tests was to defer the formation of the objectionable tread ramp near the flange in a worn tire. The design specifically allowed that there should always be a portion of the root radius still available to contact the edge radius of the rail. Diagrams representative of each of the tire contours and conditions of service are reproduced. In these diagrams, there will be noted a step developed after service at the junction of the flange root and the recess due to flange wear.